What does “just above chance” mean?

Question

Each classifier in the group is a “weak” classifier (only just above chance performance).

What does "only just above chance performance" mean?

Answer 1

You're parsing it wrong: it's “just above [chance performance]". A chance performance is what you would obtain if you performed at random. For example, if you answer a multiple choice test randomly, you will (on average) get a score that is not zero.

So, being only just above chance performance means “being only marginally better than random”. Thus, it is not very good.